Squirrelmail & ISPConfig3

I followed the Ubuntu 10.10 perfect server guide. The issue I'm having is when I type in website.com/webmail and log in I get the following error.

Code:

Error opening ../config/default_pref
Could not create initial preference file!
/var/lib/squirrelmail/data/ should be writable by user www-data
Please contact your system administrator and report this error.

If I use website.com:8080/webmail I can log in just fine. Is there a way to configure either ISPConfig or squirrelmail to allow the log in without having to use the ":8080" after the web address?